This project is designed to further purify and characterize various forms of glutamate decarboxylase (GAD), cysteic/cysteinesulfinic acids decarboxylase (CAD/CSAD) and serine-transhydroxylmethylase (serine-THM), the biosynthetic enzymes for GABA, taurine and glycine respectively, and to delineate the role of these enzymes in the regulation of the effective levels of GABA, taurine and glycine in connection with their important roles as neurotransmitters or modulators in mammalian central nervous system. The purified enzyme preparations will also serve as antigens for the production of specific antibodies, so that the GABAergic neurons and those neurons containing CAD/CSAD and serine-THM can be identified at cellular and subcellular levels by immunocytochemical methods. In addition, I also plan to perform the following studies (1) To purify the high molecular weight (MW) GAD from the cell body-enriched fraction and to determine whether the high MW GAD represents as a precursor or as a higher polymeric form of low MW GAD, (2) To elucidate the mechanism of conversion of high MW GAD to low MW GAD with special emphasis on the nature of the converting factor(s), (3) To make monoclonal antibodies against various forms of GAD (high and low MW GAD and glial GAD), CAD/CSAD and serine-THM so that sufficient quantities of antibodies will be available for immunochemical and immunocytochemical characterization of various neuronal pathways involving GABA, glycine and taurine as transmitters or modulators, (4) To elucidate the function of glial GAD and GAD in non-neuronal tissues, e.g., kidney and heart.